Jerry, I have not followed this thread very closely, but is the
reduction in gain with galvanized from resistive losses?
73, Joe
K4SAV wrote:
>An update on the 800 meter long wire performance.
>
>Using 17 ga aluminum wire vs 0.5 inch galvanized cable I had first
>assumed, decreases the gain by about 3.7 dB.
>
>The antenna pattern is very sensitive to the exact overall length.
>Looking at it another way, it is sensitive to frequency change. A
>frequency change of 50 KHz changes what used to be a peak lobe into a
>null (looking mostly at the pattern off the end of the wire). For
>example, off the end of the wire, at 1.8 Mhz and an elevation angle of
>10 degrees the gain may be -1 dB. Move to 1.85 MHz and the gain is -13
>dB, same angle.
>
>The method of feeding the wire also effects the pattern. I assumed end
>fed with the shield dropping straight down into the salt water. This
>seems to produce the best pattern I could find.
>
>Implementing a vee beam with an 80 degree included angle seems to reduce
>the pattern into something that is very scrambled and with lower gain.
>
>I am normally unsure about simulator performance when wires are close to
>the ground, but in this case since this is an almost perfect ground,
>this seems to be within the guideline of the simulator. The simulator
>shows very little difference between using perfect ground and salt water
>except between 0 and 3 degrees elevation.
>
>Jerry, K4SAV
>
>
>
>>
>>
>>
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>
>_______________________________________________
>
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>questions and ask for Sherman, W2FLA.
>
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>
>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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